It is already known to use a magnetic separator to separate magnetic particles from central heating system water, as described in granted British Patent GB2402894. It is a well understood problem that, over time, oxygen contained within the system water of domestic and commercial heating systems causes corrosion to the inner surfaces of pipes, radiators, boiler heat exchangers and the like. The corrosion results in the system water carrying ferrous particles, sometimes referred to as magnetite. Other non-magnetic particles are also carried in the system water. The magnetic and non-magnetic particles, if left in the system water, tend to build up as sludge over time and reduce the efficiency of the system. They may build up in the boiler thus reducing heat transfer, in the lower corners of radiators causing cold spots, or in pipe work causing reduced flowrate of system water and increasing the demand on the system pump.
It is known to add inhibitors to try and prevent corrosion, but often the inhibitors only slow or delay the onset of corrosion problems rather than removing them. Whilst a magnetic separator is effective in removing magnetite, it is only partially successful in removing non-magnetic particles. An advantage of, for example, the magnetic separator of GB 2402894 is that the flow of system water through the separator is hardly restricted at all and the losses in the separator are minimal. Swirl is set up in the separator around a sleeved magnet and magnetite in the system water is attracted out of the flow by magnetic attraction.
However, in order to effectively remove non-magnetic particles held in suspension, it is necessary to significantly slow the flow rate of the system water. However, it is undesirable to slow the flow rate, because this has a detrimental effect on the heating efficiency of the system. Furthermore, it is not desirable to pass the system water through a filter, such as a mesh or gauze, because this significantly impedes the flow, reduces efficiency, can clog easily and requires relatively frequent cleaning.
It is an object of the invention to provide a separator suitable for separating particles from water circulating in a closed system which substantially mitigates or reduces these problems.